Thread-cutting mechanism.



A. F. FIFIELD.

THREAD CUTTING MECHANISM.

APPLICATION FILED APR. 1. 1914.

1,251,451. Patented Dec. 25,1911.

2 SHEETS-SHEET 1.

WITNESSES: INI/EN TOR A. F. FIFIELD.

THREAD CUTTING MECHANISM. APPLICATION FILED APR. I, I914.

1,251,451. Patented B01125, 1917.

2 SHEETS-SHEET 2.

'wmvessss:

IN I/E N TOR UNITED STATES PATENT OFFICE.

ALBERT F. FIFIELD, OF ELIZABETH, NEW JERSEY, ASSIGNOR TO THE SINGERMANU- FACTURING COMPANY, A CORPORATION OF NEW JERSEY.

THREAD-CUTTING MECHANISM.

Specification of Letters Patent. Patented Dec. 25, 1917.

Application filed April 1, 1914. Serial No. 828,662.

To all whom it may concern:

Be it known that I, ALBERT F. FIFIELD, citizen of the United. States,residin at Elizabeth, in the county of Union and tate of New Jersey,have invented certain new and useful Improvements in Thread-CuttingMechanisms, of which the following is a specification, reference beinghad therein to the accompanying drawings.

This invention has for-its object to provide simple and effective meansfor severing the needle-thread at the completion of a succession ofstitches, and insuring the effective cooperation of the stitch-formingelements in the production of the initial stitches succeeding saidsevering action. The improvement, although not limited to employmentwith any particular type of stitchforming mechanism, is speciallyadapted to that class of sewing machines employing a reciprocatingneedle and a loop-taker adapted to detain thread-loops seized in oneneedlethrust until the succeeding needle-thrust.

According to the present invention, in its preferred form, a singlechain-stitch rotary looper cooperates with the needle in the productionof stitches, and needle-thread nipping means are provided between theneedle and thread supply, and a thread-severing implement is mountedbeneath the workplate and intermediate the needle and looper,

means being provided for effecting the simultaneous action of thethread-nipping and severing means upon the needle-thread at thecompletion of the final stitch-forming cycle of a group or succession.The needle-bar is preferably provided with a laterally offset thread-eyeacting in conjunction with fixed thread-guides as a take-up orstitch-setting element, and intermediate the same and the tension deviceis disposed an eyed slack-producing thread-arm having an operativeconnection with a controlling cam whereby a reserve length of thread isdrawn from the thread-supply through the tension preparatory to athread-severing action and is given up in the initial stitch-formingcycle of a' succeeding group or succession to provide slackneedle-thread for beginning the series or succession of stitchesfollowing such thread-severing action.

The invention will be understood by ref erence to the accompanyingdrawings, in which Figure 1 is a rear side elevationio'f a fiat-buttonsewing machine of the "well tion of its actuating means. Fig. 6 is asec--.

tional plan view ofthe face-plate of the bracket-arm with theneedle-thread nipping device, and Fig. 7 is an enlarged detail viewshowing a portion of the nipper-actuating means.

The machine shown in the drawings is of that class represented in theUnited States Patent to J. J. Sullivan N 0. 777,561, of December 13,1904, and contains the stitchforming mechanism of my application filedApril 1, 1914, Serial No. 828,663. The frame is constructed with theusual bed-plate 1 and bracket-arm composed of the hollow standard 2 andtubular overhanging arm 3 terminating in the head 4: in which isjournaled the needle-bar 5 carrying the eye-pointed needle 6 whichcooperates with the rotary single-chain-stitch looper 7 secured upon therotary shaft 8 journaled beneath the bedplate.

The looper-shaft 8 carries upon its rearward end the transverselygrooved pulley 9 connected by means of the belt 10 with a similar pulleyupon the main-shaft mounted in the bracket-arm and provided upon itsrearward end with the loose grooved pulley 11 and the fixed groovedpulley 12 having connected therewith the stopping cam 13 formed with theshoulder 14 and adjacent peripheral recess 15. Cooperating with the cam13 is the tapered upper extremity 16 of a spring-pressed plunger-barcarried by the vibratory lever 17 which is pivotally mounted by means ofthe cross-pin 18 within a transverse slot of the rocking plug 19journaled in a fixed socket 20.

The lever 17 is yieldingly maintained in contact with a suitable seatof'the'bracket member 21 by means of the pin 22 pressed against theopposite face thereof by means of the surrounding spring 23 within thetransverse socket 24 of the bracket member 25 The lever 17 is normallypressed into" i the range of a'ctionof the'cam 13 by a spring in Fig. 1,by a spring-pressed catch lever 26. The stop-lever 17 is adapted to bethrown into retracted position by an angle-lever fulcrumed at 27 uponthe bracket members 21 and 25 and comprising the lateral arm 28apertured to receive the usual treadle-rod and the depending arm 29whose extremity rests upon the rear side of the lever 17.

The machine is provided with the usual controlling cam 30 fulcrumed at31 upon the standard 2 and driven by a suitable connection with themain-shaft, this cam having upon its inner face one or more trippinglugs 32 adapted for engagement with the tail of the catch-lever 26 torelease the stopping lever 17 in stopping the machine. Suitableconnections are shown between the cam 30 and the work-holder forimparting to the latter the requisite work-shifting movements relativeto the stitch-forming mechanism.

Secured upon the under face of the throatplate 33 is the bracket-piece34 having an offset portion carrying a fulcrum-stud 35 entering anaperture in the throat-plate and having journaled thereon an angle-leverformed with the lateral arm 36 and the longer longitudinally extendingarm 37 affording the shank of the transversely extending hookedthread-engaging implement 38 of which the throat 38' may be sharpened toform a knife-edge for engaging and severing one limb of a needle-threadloop detained around the body of the looper 7 as represented in Fig. 5.The thread-engaging implement 38 has'a path of movement upon thefulcrum-stud 35 across the elongated needle-aperture 33 of thethroatplate.

The arm 36 of the angle-lever has a depending pin 39 embraced by theforked extremity 40 of a transverse arm 41 of the cutter-actuating bar42 mounted in suitable bearings 43 beneath and longitudinally of thebed-plate and provided at its rearward end with the depending stud 44.The stud 44 is embraced by the forked extremity 45 of the lateral arm 46of a bellcrank-lever mounted upon the fixed fulcrum-stud 47 del per 51to throw the driving belt from the loose pulley 11 to the fast pulley12, the arm 17 of the stop-lever is temporarily retracted from the pin49 until the catch-lever 26 is tripped to restore the stop-motion deviceto stopping position when the aperture 50 of the arm 17' again embracesthe pin 49 and in the side-throw of the stop-lever in 0pp0sition to thebuffer-spring 23 under the momentum of the moving parts, the bellcrank46 48 is rocked, and through the bar 42 the thread-severing implement 38is shifted from the full line position represented in Fig. 5 temporarilyto dotted line position, so as to cause the operative portion 38 toseize and sever one limb of the needle-thread loop a, after which therecoil of the lever 17 under the action of the spring 23 restores theparts to their full-line position.

To insure the severing of the thread under such action of the implement38, the face-plate 52 of the bracket-arm head has secured thereon byscrews 53 the superposed nipper-plates 54 and 55, the inner one havingthe upturned lips 56 embracing the edges of the superposed plate andprovided with thread-guiding notches 57, the free end portion of theouter plate being spaced slightly from the inner plate to normallypermit the free passage of the thread through the guide-notches 57.

Secured to the inner face of the faceplate 52 also by means of thescrews 53 is a block 58 forked to receive an inwardly pro ecting portion59 of the curved nipperlever 60 fulcrumed therein by means of thecross-pin 61. Suitably mounted upon the rearward side of the bracket-armis the twopart push-rod 62 of which the forward end is adapted to enteran aperture in the faceplate and to engage the extremity of the rearwardarm of the nipper-lever 60 whose forward arm is adapted to press uponthe outer member 55 of the thread-nipper to nip the thread passingbeneath the same. The rearward extremity of said push-rod 1s shown (Fig.7) slightly rounded at one s1de for engagement with the beveledextremity 63 of an arm 64 secured upon and moving with the stop-lever17.

The two parts of the rod 62 are normally pressed apart by the spring65surrounding the forward section and interposed between the collar 66thereon and the socketed end 67 of the-other section in a manner wellknown, to afford a-yielding connection between the parts. Thethread-nipper is normally open,'and therefore inactive upon the thread,in which condition it remains throughout each stitching operation, butJust as the stop-lever 17 is tilted sidewise 1n finally arresting theoperation of the machine, it acts through its described independentconnections to simultaneously effeet the nipping of the thread and theoperative movement of the severing implement 38, WhlCh latter acts upona section of thread secured to the material at one end from wh1ch itpasses around the looper and extends upwardly through the now closednipper, thereby preventing a possible failure of the severing action.

As the last thread-loop of the series or succession has the one of itslimbs attached to the work severed by the implement 38, a suflicient endof thread would not be normally left to provide for the initial stitchof a new series, and one part of the present invention consists of meansfor drawing off from the thread-supply sufficient thread for suchpurpose.

The needle-bar is shown provided with a laterally apertured take-up arm68 through which the thread is normally led from the tension device 69sustained by the bracket 70 upon the top of the tubular arm 3. Se-

cured also upon the bracket is a forwardly extending arm 71 having athreadguiding cross-member 72 which in practice may have an elongatedthread-aperture formed therein.

Journaled upon the bracket 70 concentrically with the tension device 69is an angle-lever formed with a forwardly extending arm 73 having at itsextremity an apertured lateral ear 74 and provided with an upwardlyextending arm 75 connected by the link 76 with the upper arm 77 of arock-lever fulcrumed upon the stud-screw 78 and provided with thedepending arm 79 having a lateral nose adapted for engagement with thestepped cam-plates 80 secured by screws 81 upon the periphery of thecontrolling cam 30. The rock-lever is maintained with the nose of itslower arm in contact with the periphery of the cam 30 and cam-plates 80by means of a spring 82. The cam-plates 80 are so arranged andproportioned that during each of the last several stitches of a group orsuccession the rock-lever 77 79 is shifted slightly so as to lift thethread-arm 73 progressively until at the completion of the final stitchit assumes the dotted line position represented in Fig. 1, the take-upmember 68 serving, not only to set the stitch in performing its normalfunction, but to draw an excess of thread from the thread-supply throughthe tension proportionately with each upward step of the guide-member 74 until an amount is provided sufiicient to compensate for the severingof the thread beneath the work. In the operation of th machine for theinitial stitch of a succeeding group, the nose of the rocklever arm 79rides down the inclined higher end of the cam-plate and causes thelowering of the thread-arm 73 to initial position in a single step,thereby providing slackthread to enable the first thread-loop presentedby the needle to be seized and distended by the looper without havingthe thread end drawn through the fabric and the loop thus destroyed byaction of the take-up. In this stage of the initial stitchforming cycle,the slack thread provided intermediate the needle and the tension de--vice robs the take-up arm of its normal action in tightening the threadleading from 'action.

the needle-eye to the work, and its action is thereby made ineffectivein the same manner as would be the case were its movement actuallytemporarily suspended.

It is obvious from the foregoing description that the present inventionis not limited to the specific mechanism herein shown and described foractuating the thread-severing implement, the thread-nipper ortheslackproducing element, and that these elements are not restricted touse in machines of any particular type or in connection withstitchforming mechanism of any particular class. It is evident that, incase the thread-severing means is employed in conjunction withlock-stitch mechanism, such aS that of the said Patent No. 777,564, somemeans such as that disclosed in said patent may be used,

in lieu of the chain-stitch. looper of the present mechanism, fordetaining the final needle-thread Loop preparatory to the severingaction in the position of the various parts corresponding with theretraction of the needle to its highest point, or normal stoppingposition.

While the operative portion 38' of the thread-severing implement isadapted to be sharpened so as to make a clean cut, as before indicated,it is represented in the drawings blunt-edged so as to be capable ofsevering the needle-thread loop by a tearing Regardless, however, of thecharacter of the work-engagingporti/on of the severing implement, itspositive action upon the thread is insured by the employment of thethread-nipper. V c

Having thus set forth the nature of the invention, what I claim hereinis:-

1. In a sewing machine, the combination with stitch-forming mechanismcomprising a needle and a cooperating loop-taker, of a thread-nipper, athread-severing device operated independently of the threadnipper andadapted for engagement with the needle-thread intermediate the needleand the loop-taker, and operating means for causing the thread-nipper tonip the needle-thread and for simultaneously causin the severing deviceto sever the needlethread-nipper to nip the needle-thread and jforsimultaneously causing the severing device to sever the needle-thread.

3. In a sewing machine, the combination with stitch-forming mechanismcomprising a reciprocating needle and a cooperating loop-taker adaptedto detain needlethread loops while the needle is out of the work, of athread-nipper, a thread-severing device operated independently of thethread-nipper and having an implement adapted to engage the threadintermediate the needle and the loop-taker, and operating means forcausing the thread-nipper to nip the needle-thread. and forsimultaneously causing the severing device to sever the needle-thread.

4. In a sewing machine, th combination with work-supporting means andstitchforming mechanism comprising a reciprocating needle and acooperating loop-taker adapted to detain needle-thread loops while theneedle is out of the work, of a threadnipper disposed at the side of theworksupporting means farthest from the loop taker, a thread-severingdevice having an implement adapted to engage the thread in termediatethe needle and the looptaker, and operating means for causing thethreadnipper to nip the needle-thread and for simultaneously causing thesevering device to sever the needle-thread.

In a sewing machine, the combination with stitch-forming mechanismcomprising a reciprocating needle and a cooperating loop-taker adaptedto detain needle-thread loops while the needle is out of the work, of athread-nipper, a thread-severing device having an implement adapted toengage the thread intermediate the needle and the looptaker,nipper-actuating means, severing-device actuating means independent ofsaid nipper-actuating means, and a common reciprocatory member forcausing the threadnipper to nip the needle-thread and for simultaneouslycausing the severing device to sever the needle-thread, whereby asection of needle-thread held between the loop-taker and the nipper issevered by said thread-engaging implement.

6. In a sewing machine, the combination with stitch-forming mechanismand a cooperating loop-taker, and a stop-motion therefor including arotary cam and a vibratory lever adapted to engage the same, of athread-nipper, a thread-severing device having an implement adapted toengage the thread intermediate the needle and the looptaker, andconnections between said lever and the nipper and severing device,respectively, for causing them to simultaneously engage theneedle-thread.

7. In a sewing machine, the combination with stitch-forming mechanism,actuating means therefor, and a stop-motion including a rotaryshouldered cam operatively connected with said actuating means, and avibratory lever movable into, out of and within the range of action ofsaid cam, of a thread nipper, a thread-severing device having animplement adapted to engage the thread intermediate the needle and theloop-taker, and connections between said lever and the nipper andsevering device, respectively, where by lateral movements imparted tosaid lever by said cam are communicated to the nipper and severingdevice for their simultaneous nipping and severing action upon thethread.

8. In a sewing machine, the combination with stitch-forming mechanismcomprising a needle and a cooperating loop-taker, controlling means fordetermining the period of action of the stitch-forming mechanism, and aneedle-thread take-up, of a thread-cutting device, actuating meanstherefor controlled by the said controlling means, and meansacting toform slack in the needlethread whereby the take-up is renderedineffective for normal action upon the needlethread in thestitch-forming cycle immediately succeeding a thread-severing action.

9. In a sewing machine, the combination with stitch-forming mechanismcomprising needle and a eoiiperating loop-taker, controlling means fordetermining the period of action of the stitch-forming mechanism, aneedle-thread tension, and a take-up acting upon the needle-threadintermediate said tension and the needle, of a thread-cutting device,actuating means therefor controlled by the said controlling means, andmeans acting near the completion of the final stitch. preceding athread-severing action for drawing oiii a supply of thread between thetension and the needle and releasing the same to produce slack in thestitch-forming cycle nextsucceeding said thread-severing action.

10. In a sewing machine, the combination with stitch-forming mechanismcomprising a needle and a cooperating loop-taker, controlling means fordetermining the period of action of the stitch-forming mechanism,

' a needle-thread tension, and a take-up acting upon the needle-threadintermediate said tension and the needle, of a thread-cutting device,actuating means therefor controlled by the said controlling means, andmeans acting during a succession of stitch-forming cycles immediatelypreceding each cutting action in drawing ofi a supply of thread betweenthe tension and the needle and for releasing the same to produce slackin the stitch-forming cycle next succeeding said thread-severingaction.-

11. In a sewing machine, the combination with stitch-forming mechanismcomprising a needle and a cooperating loop-taker, controllin means fordetermining the period of action of the stitch-forming mechanism,

a needle-thread tension, and a take-up acting upon the needle-threadintermediate said tension and the needle, of a needle-thread cuttingdevice, needle-thread nipping means, actuating means for simultaneouslyoperating the nipping means and cutting device, and means actingbeforethe completion of the final stitch preceding a thread-severing actionfor drawing off a supply of thread between the tension and the needleand releasing the same to produce slack in the stitch-forming cycle nextsucceeding said thread-severing action. 12. In a sewing machine, thecombination with titch-forming mechanism comprising a needle and acooperating loop-taker, a needle-thread tension, a take-up acting uponthe needle-thread intermediate said tension and the needle, and astop-motion comprising a rotary cam and a vibratory lever adapted toenga e the same, of a needlethread cutting d vice, needle-thread nippingmeans, actuating means for said nipping means and thread-cutting deviceconnected with and actuated by said vibratory lever, slack-threadproducing means operatively engaging the needle-thread intermediate thetension and the needle preparatory to a cutting action and releasing thesame in the stitch-producing cycle succeeding said cutting action, and acontrolling cam provided with stop-motion tripping means and with meansfor operating said slack-thread controlling means.

In testimony whereof, I have signed my name to this specification, inthe presence of two subscribing witnesses.

ALBERT F. FIFIELD.

